Bypass the op-amp input buffer - only Audiophonics?

Thank you. The Audiophonics option of bypassing the input buffer proved unneeded to me. The RME ADI FS-2 DAC can be set at -5, -1, +7, or +13 dBu, and the Boxem class D amp, for example, offers input sensitivities of 9.4, 3.74, or 1.79 V at 8 ohms, so I guess that it is more than enough flexibility.

Some Class D amps natully  have very low input impedance, the input buffers are there to make them look more like other amps and give OEMs a chance to differentiate themselves.  Check the resulting input impedance before deciding